In mechanisms comprising a freewheel it is frequently desirable to prevent torque transmission from one to the other of the elements connected to the freewheel, and to allow free rotation in both directions of one element. When, for example, double acting freewheels are used in four wheel driven motor cars there is a problem to avoid jamming if the freewheel, e.g. due to the driving wheels slipping, is in torque transmitting operation when the vehicle is stopped and the direction of propulsion is then reversed. A car wheel connected to the freewheel is in normal operation, i.e. when no slip occurs, rotating faster than the car wheel drive shaft from the motor which is connected to the freewheel and if the freewheel is torque transmitting when stopped, then at the start in the reversed direction the motor acts as a brake for the car wheel, and the freewheel is not disengaged until the drive shaft rotates faster than the car wheel.
Existing proposals for solving this problem comprise electric and hydraulic systems, which are complicated and expensive.